1. Field of the Invention
The present invention relates to a method for producing a porous body, a porous body, and a honeycomb structure.
2. Description of the Related Art
As the method for producing a dense sintered silicon carbide ceramic body, a method has been known in which alumina, which is a sintering aid, in an amount in the range of 2% to 25% by weight, is mixed to silicon carbide, molding is performed at a pressing pressure of 2,000 kg/cm2, and hot-press sintering is performed in an argon gas atmosphere at a firing temperature of 1,900° C. under a pressure of 200 kg/cm2. For example, in the method described in JP-A 60-239360, since sintering of silicon carbide is accelerated by alumina, the firing temperature can be decreased and a sintered body having high strength at room temperature can be obtained. However, the sintered body produced by this method has a problem in that, in contrast with the strength at room temperature, the bending strength at 1,400° C. decreases. On the other hand, in the production method described in JP-A 63-190758, alumina in an amount in the range of 1% by weight or less is mixed to silicon carbide, molding is performed at a pressing pressure of 7,000 kg/cm2, and sintering is performed in an argon gas atmosphere at a firing temperature of 1,900° C. under normal pressure. In the sintered body obtained by this method, presence of aluminum is not observed in grain boundaries of silicon carbide, and the bending strength at 1,500° C. is higher than the bending strength at room temperature. The entire contents of JP-A 60-239360 and JP-A 63-190758 are incorporated herein.